He was a close friend and business partner of Prescott Bush. Mallon attended Yale University where he and Bush both became members of the Skull and Bones in 1917. George Herbert Walker Bush (S&B 1948) would later name his own son Neil Mallon Bush after the man who had given him his first job out of Yale. Mallon was also an early investor in Zapata Corporation, founded by Bush.

The Mallon family was based out of Cincinnati, Ohio and was reportedly close with the Taft family, particularly William Howard Taft.